Pradimicin-IRD from Amycolatopsis sp. IRD-009 and its antimicrobial and cytotoxic activities.

A new polycyclic antibiotic, pradimicin-IRD, was isolated from actinobacteria Amycolatopsis sp. IRD-009 recovered from soil of Brazilian rainforest undergoing restoration area. This molecule is the major compound produced in solid culture media. The new compound was detected by a focused method of precursor ion (high-performance liquid chromatography coupled to tandem mass spectrometer) developed previously to identify unusual aminoglycosyl sugar moieties. The compound was isolated and its structure was, therefore, elucidated by high-resolution mass spectrometry, and 1D and 2D nuclear magnetic resonance experiments. Pradimicin-IRD displayed potential antimicrobial activity against Streptococcus agalactiae (MIC 3.1 µg/mL), Pseudomonas aeruginosa (MIC 3.1 µg/mL) and Staphylococcus aureus (MIC 3.1 µg/mL), and also cytotoxicity against tumour and non-tumour cell lines with IC50 values ranging from 0.8 µM in HCT-116 colon carcinoma cells to 2.7 µM in MM 200 melanoma cells. Particularly, these biological properties are described for the first time for this chemical class.